The invention relates to a device for microfilming bound volumes. The term "volumes" is to be construed in its broadest sense so as to include not only printed works, in the form of texts, but also any works of illustrative and photographic representations, drawings, plans, tables, formulas and the like.
In addition to facilitating the production of reprints or facsimiles, another very important use for the device is for microfilming bound volumes having unique or special characteristics. There exists an ever-increasing need for such microfilming. It is especially important for the microfilming of old and valuable books, as many of them, because of paper quality, are disintegrating over time even when they are protected and carefully maintained. Indeed, in many cases, the disintegration can be prevented or, at least, considerably slowed by modern preservation procedures. However, the number of such valuable books is so great that it is quite impossible to preserve all of them in a proper manner. Thus, to retain, at least, the content and appearance, as well as the composition, of these works for future generations, a process of archiving on microfilm has been attempted and has proven successful. The microfilming serves not only the function of archiving, but also makes the contents of such valuable books available and accessible to scientists, students, teachers and other interested persons.
The current methods and devices for microfilming bound volumes, especially old books, are less than satisfactory for several reasons. One reason, which is addressed in this specification, is the difficulty of making reproductions true to the original to a very high standard.
The simplest method of microfilming is to photograph two adjacent pages simultaneously as the book is spread open against a glass plate. However, in many cases this is not possible. As one knows from photocopying an open book spread against a glass plate, a lip-like bead is formed over the spine and it is difficult to photograph the inside area sharply, clearly and without distortion. This is especially true at the ends of the lines of the opposing pages where they come together at the binding. This problem with distortion increases proportionally as one stack of pages becomes smaller and the other stack of pages becomes larger. For instance, when one is copying from a book of 500 pages and pages 10 and 11 are to be photographed simultaneously, the arrangement beneath the projection plane is such that one stack of pages includes the book cover and five pages and the other stack of pages, to the opposite side of the middle line of the spread-open book, contains 245 pages and the other book cover. A horizontal plane of photography can thus be attained only if the pages of the book supported beneath the horizontal plane, in the stack of lower height, as compared with the stack of greater height, are specially supported. This support requires a height compensation mechanism that can be continually adjusted. Such a mechanism is involved and complicated.
The aforementioned difficulty increases considerably in the case of many of the old and therefore valuable books. In earlier times, for economic reasons, as much width as possible of each page was used. The written text and displayed images extended as far as possible toward the edges of the pages. That means, in old books, where the adjacent pages are abutted at their inside edges, reproduction free of distortion has been impossible. What is true with new volumes, which have no text and no image representation in that area, has been a quite impossible situation with old books, as both text and illustrations to be photographed are located where they can't be reached.
A further difficulty in microfilming, in accordance with the current art, arises in that the back of the book, its spine, is greatly stressed during the process and sometimes overstressed. With old books, especially, this stress often cannot be withstood. In such cases, to preclude damage, one is forced to photograph the book page by page, that is, one page at a time. To do so, the book is positioned opened with the stacks of pages disposed at a right angle to one another. The stack of pages lying horizontal is guided beneath a glass plate, while the vertical stack of pages must be held manually. When the vertical stack of pages comprises a voluminous folio, it is a physically difficult job. Also, this arrangement requires that the microfilm be rotated 180.degree. for each second page which greatly degrades the microfilm readability.
A copy-holder for bound volumes to be microfilmed is disclosed in U.S. Pat. No. 1,175,221. The copy-holder consists of two support plates fixedly arranged perpendicular to one another, which limits the work space to two sides. The book to be photographed is placed into the work space. Although the two support plates have a hinge attaching them to the frame, the copy-holder can be tilted only within a very limited range. As shown in FIG. 1 of the U.S. Pat., stop boards or some sort of stop mechanisms are provided on the frame to prevent tipping of the copy-holder more than approximately 45.degree..
European Pat. No. 0 149 897 A2 discloses a photocopier with a book support. The book support rests on a traverse guide which can be raised and lowered to be pressed against the bottom surface of a glass plate found in the work space. The book support consists of two plates which are perpendicular or almost perpendicular to each other and is rotatable around a vertical axis so that, after the top page of the stack of pages on the side of the book engaging the plate have been photographed, the support is rotated 180.degree. and the top page of the opposite stack of pages can be photographed. This rotation of each second photocopied page reverses photographed opposite pages by 180.degree., which makes the resulting microfilm products practically unusable.